In related art, PTL 1 discloses a vehicle brake mechanism in which an EPB and a service brake that is formed by a hydraulic brake device are combined. In this brake mechanism, when the EPB is actuated and released, the EPB and the service brake that uses hydraulic pressure are used at the same time. Thus, the volume of the EPB is reduced and size reduction and cost reduction are attained. Specifically, when the EPB is actuated and released, the brake fluid pressure in a wheel cylinder (hereinafter referred to as a W/C) is increased (hereinafter referred to as back-up pressurization) by the service brake, a piston in the W/C is pressed, and a load applied to a motor of the EPB is reduced. Thus, the actuation and release of the EPB can be performed even when the output of the motor is reduced. Further, a road slope angle and a load weight etc. are detected in advance. Based on these pieces of information, the necessity for hydraulic assist when the EPB is actuated and released, and a hydraulic pressure value to be generated by the service brake when the hydraulic assist is necessary are estimated, thus generating an appropriate hydraulic pressure by the service brake.